Drilling in the earth, particularly in coal, shale, slate, and like formations



Dec. 10, 1929. J. A. M cwcAR 1,738,594

DRILLING IN THE EARTH, PARTICULARLY IN COAL, SHALE, SLATE, AND LIKE FORMATIONS Filed March 30, 1926 Zoar.

Patented Dec. 10,, 1929 UNITED STATES PATENT" OFFICE,

JOHN ANGUS MAOVICAR, OF LONDON, ENGLAND, ASSIGNOR TO SULLIVAN MACHINERY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF MASSACHUSETTS DRILLING In THE EARTH, PARTICULARLY IN COAL, SHALE, SLATE, AND LIKE FORMATIONS Application filed March 30, 1926, Serial No.

This invention relates to an improved method of drilling in the earth, as when prospecting for minerals and relates particularly to drilling in coal, shale, slate and like formations. The process of cementing when drilling in ground which is soft or liable to cave in, is well known, but it has never proved satisfactory in a coal formation; the reason is that the cement when set frequently proves to be harder than the shales, slates and other natural materials, so that in re-drilling the hole through the cement, the drill runs off into the softer material, changing the direction of the hole to such an extent that the original hole drilled below the soft ground is not regained. Furthermore, the deflection alone may be quite undesirable.

The object of this invention is to provide an improved method of avoiding this difficulty and rendering it possible effectively to use the cementing process in coal and like formations where the above difficulties arise.

According to this invention, the improved method'of cementing and redrilling, consists in cementing in the drill-hole a rod of a size small enough to enter the drill, drilling over it as a guide through the cement and then removing the guide-rod like a core.

Another feature of this invention consists in locating the guide-rod centrally in the hole by means of collars which fit the hole and are applied to the guide-rod before it is inserted therein. These collars may be formed ofcement or other suitable'ma-terial.

The above and other features of the invention relating to modifications in the apparatus, for the purposes set forth, will now be described with reference to the accompanying drawing, in which Figure 1 is a sectional view showing diagrammatically a part of a drill hole with the guide-rod cemented in position therein.

Figure 2 is a sectional View showing the method of coupling the lengths of guide- 45 rod, and

ily drilled through, these collars being spaced 98,610, and in Great Britain May 20, 1925.

Figure 3 isa plan of the parts shown in Figure 2.

Assuming that a hole 1 has been drilled, for example through some coal or like formations 2 which are found to be caving, the procedure according to this invention is as follows. A guide-rod 3, which may be a length of smaller drill rods, is inserted in the drill hole to extend through the particular region which is caving and which it is desired to cement. In order to locate the guiderod centrally in the hole when inserted in it, the rod is provided with collars 4 of cement or other suitable material which can be readat suitable intervals along the length of the rod. Each collar has a number of holes 5 through it for the passage of the cement slurry, which is poured into the hole around the guide-rod, so that when the cement is set the guide-rod is retained centrally in the hole. The cement is indicated at 6. Alternatively, the affected region of the hole may be cemented in any ordinary or convenient manner so as completely to fill the drill hole in that part with cement and whilst the cement is still fluid, a length of guide-rod may be inserted so as to extend centrally through it. In any case the size of the guide-rod is selected so that the core-drill used for the hole will pass over the rod and receive it within it like a core. The original core-drill is used for re-drilling through the cement and it passes over" the rod which thus serves as a guide to maintain the drill in its true direction. When the full available length of the core has been drilled the drill is lifted in the usual manner and draws up with it the guide rod as if it were a core. I

If the length of guide-rod required is greater, as it frequently will be, than the length of core which can be accommodated within the drill, several sections of guide rod are secured together in such a manner 90 removed in sections when the core-drill is lifted, A convenient form of coupling for the guide-rods, which as previously stated are preferably smaller size drill-rods, is illustrated in Figure 2. In this form the guiderods 3 are joined by a coupling member 7, of wood or other suitable material, which engages frictionally the usual coupling threads 8 within the rods. This form of coupling provides a temporary joint to be inserted in the hole and to hold them in alignment therein but which 1S easily broken when the core drill is lifted, thus carrying with itthe separated guide-rod section. It will be understood that any desired length of guide-rods can be drilled over in this manner, the various sections of guide-rod being removed one by one each time the drill is lifted.

As shown in Figure 2 a cement collar 9 surrounds the guide-rods at the joint and such collars may be used instead of, or in addition to the collars 4, for locating the line of rods centrally in the hole. The collars 9 are fixed on the rods, as by cementing them thereto, before the rods are inserted in the hole, and each collar has holes 10 passing through it like the collars 4 previously described.

It will be seen that the method herein oescribed. of re-drilling a cemented drill-hole,

' ensures that the original alignment of the hole is accurately maintained, and consequently there will be no difliculty in getting back into the hole originally drilled below the caving. lVhile the method is particularly useful in drilling in coal and like formations it will be understood that it is generally applicable to drilling in any ground Where it is necessary to cement and re-drill a hole for any reason.

I claim:

1. A method of cementing and re-drilling, consisting in cementing in the drill-hole a rod of a size to enter the drill, drilling over it as a guide through the cement and removing the guide-rod like a core.

2. A method of cementing and re-drilling which consists in locating a guide-rod .centrally in the drill hole. filling in liquid cement around the guide-rod, drilling throughthe cement when set with a coredrill which passes over the guide rod, and removing the guide-rod fromthe hole.

3. In a method according to claim 1, loeating the guide-rod centrally in the hole b means of collars formed of readily drillab le material, substantially fitting the hole, and applied to the guide rod before insertion in the hole.

4. In a method according to claim 2, lo-

,gether in such manner that 'pulled apart when in the hole by the action sufliciently' strong and rigid to enable the lme of rods in the hole by means of cement collars su ting the hole, the latter is inserted in the hole.

5. In a method according to claim 1, coupling a number of guide-rod sections toof lifting the core-dri ll.-

6. In a method according to claim 2, coupling a number of guide-rod sections together in such manner that they can be pulled apart when in the hole for successive removal by the action of lifting the core-drill.

7. A guide rod for core drills, for fixation centrally in a drill hole, and of'a size permitting passagethrough a 'core lifter and entrance into a core barrel, said guide rod comprising a plurality of guide sections, and means for coupling said guide sections together to maintain the same in connected relation during location of the guide rod in the drill hole and to permit separation of the guidesections for piecemeal withdrawal from the drill hole, said coupling means being materially weaker than said guide sections and readily frangible by the application of force less than the maximum transmissible through the core lifter. r

8. A guide rod for rotary drills, for fixation centrally in a drill hole, and of a size permitting passage through the hollow drill bit of a rotary drill, said guide rod comprising a plurality of guide sections, and means for coupling said guide sections together to maintain the same in connected relationaluring location of the guide. rod in the drill hole and to permit separation of the guide sections for piecemeal withdrawal from the drill hole, said coupling means being materially weaker than said guide sections and readily frangible so that said sections may be pulled apart when in the drill hole for successive removal from the hole.

9. A guide-rod for core drills of a diameter to permit its receptionin a core barrel comprising aplurality 01. sections, readily :t'racturable connecting elements holding said sections together in predetermined relation, and reinforcing and guiding collars surrounding adjacent ends of said sections.

10. A guide-rod for core drills having a guiding and centering ring supported thereon, said ring being of readily drillable material and traversed by at least one passage connecting its upper and lower surfaces and affording a passage for fluid cement material therethrough.

11. A method of centering-and guiding a rotary drill, which consists in locating a guide rod centrally in the drill hole, securing the guide red when so located in the and applied to the rod before they can be hole, drilling with a. rotary drill which passes over the guide rod, and removing the guide rod sectionally from the drill hole. I

12. A method of cementing and re-drill- 5 ing, which consists in locating a guide rod centrally in the drill hole, fillin in H uid cement around the guide r dril 'ng through the cement when set with a core drill which passes overthe guide rod, and removing the guide rod sectionally from the drill hole. In testimony whereof I aflix my signature.

JOHN ANGUS MAOVICAR. 

